Explosion proof switch housing



Feb. 3, 1959 R. c. BERRY 2,872,552

EXPLOSION PROOF SWITCH HOUSING Filed June 12, 1957 INVENTOR.

RIcHARD C. BERRY EXPLOSION PROOF SWITCH HOUSING Richard C. Berry, Camillus, N. Y., assignor to Cronse- Hinds Company, Syracuse, N. Y., a corporation of New York Application June 12, 1957, Serial No. 665,213

3 Claims. (Cl. 200-172) This invention has as an object and relates to an explosion proof switch housing of the type wherein the switch and the switch actuating mechanism are contained within the housing, and wherein the switch actuating mechanism is operable externally of the housing. As is well known these switch housings are needed in many industrial applications wherein the atmosphere is explosive and it is necessary to enclose all electrical connections in order that any spark resulting therefrom will not ignite the explosive atmosphere. As is well known the most convenient way to enclose electrical connections is in explosion proof housings which have a flame extinguishing path so that any explosion taking place within the housing will be extinguished by the flame travel to the atmosphere through a long tortous threaded path and in the past when it has been necessary to enclose a switch of the push button type in an explosion proof housing two types of switch actuating mechanisms have been used.

The first of these comprises a construction wherein an operating shaft which extends through the cover of the housing had a horizontal bar attached thereto and when the shaft was rotated the horizontal bar would be rotated and would push the buttons downward with a very little side thrust due to the horizontal component of motion.

This solution however became impractical when thicker flanges had to be provided and the shaft had to be placed higher up in the housing. This resulted in the problem that the horizontal component of motion at the end of the horizontal bar, when the push buttons were operated, was greater than the vertical component of motion and was therefore impractical.

Consequently a second method of operating these switches in an explosion proof housing was developed comprising a rack and pinion type mechanism. In this construction the operating shaft was provided at its inner end with a pinion which was positioned between two racks so that when the pinion was rotated the racks would be moved in parallel vertical motion whereby one of the racks would depress one of the switch buttons. This solution also proved impractical since it was found in practice that the rack and pinion type mechanism proved impractical for the reason that it was costly to construct.

Accordingly it is an object of this invention to provide a switch operating mechanism for switches of the type, wherein the operating shaft may be placed at a distance from the buttons, and wherein the buttons still may be conveniently depressed by the operating mechanism.

More specifically it is an object of this invention to provide a parallelogram type operating mechanism which is simple, inexpensive and economical to construct and has a relatively long useful life in the operation.

The invention consists in the novel features and in the combinations and constructions hereinafter set forth and claimed.

In describing this invention, reference is had to the 2,872,552 Patented Feb. 3, 1959 accompanying drawings in which like characters designate corresponding parts in all the views.

In the drawings:

Figure 1 is a plan view of the switch housing with a portion of the cover shown broken away.

Figure 2 is a cross section taken on line 2-2, of Figure 1.

Referring now to the drawings it will be seen that the switch housing is made up of two parts, a receptacle 10 and a cover 11. The cover 11 is threadedly mounted on the receptacle 10 as at 12 in order to provide a flame extinguishing path between the interior of the housing and the exterior atmosphere. As will be seen from Figure 2 a sealing gasket 13 is provided between the cover 11 and the receptacle 10 to also aid in extinguishing any flame which might result froman explosion in the housing and the cover 11 is fixed against rotation on the receptacle 10 by means of the set screw 14.

A switch 16 of the push button type having push buttons 17 and 18 is mounted in the receptacle 10 by means of the strap 19 which is fixed to the bosses 20 formed within the receptacle by means of the fasteners 21.

Carried by the cover 11, in a manner which will be described hereinafter, is the parallelogram switching mechanism made up of a pair of arms or links and 26 which are aligned with the push buttons 17 and 18 respectively. Pivotally connected to the arms 25 and 26 are a pair of cross bars 27 and 28. The pivotal connection between the cross bars 27, 28 and the links 25 and 26 is effected by the four rivet pivots 30. As will be seen the cross bar 27 is notched centrally in its upper edge as at 31 and the cross bar 28 is also notched centrally in its lower edge as at 32.

As will be seen from Figure 1, the cover 11 is provided with a threaded hub 12 through which a threaded operating shaft 35 is journalled for oscillation. Mounted on the outer end of the operating shaft 35 is a handle 36 having a pair of ears 37 and 38 for rotating the shaft 35. The inner end of the shaft 35 has a pair of flat surfaces 37 formed adjacent the termination of the shaft 35 as at 38. As seen from Figure 2, the flats 37 on the shaft 35 are mounted in the notch 31 on the cross bar 27 in order to effect oscillation of the bar 27 upon oscillation of the shaft 35.

As seen best in Figure 1 an alignment strap or pivot member 40 is mounted directly below the shaft 35, and the strap 40 is atfixed to the cover 11 by means of a pair of fasteners 41 which fix the strap 40 to bosses 42 formed in the cover 11. The center of the strap 40 is formed with notches 45 which are received in the notch 32 on the cross bar 28 to provide a pivot for the bar 28. As is therefore obvious, the alignment strap 40 by reason of the fact that it is fixedly mounted in the cover 11 sup.- ports the cross bar 28, and also the arms 25 and 26 as well as the cross bar 27 in a fixed position in the cover 11.

As is apparent the operation of the device is as follows. When either of the ears 37 or 38 are depressed the shaft 35 is rotated. This rotation is transferred through the flats 37 and the notch 31 to the cross bar 27 and this rotational movement of the cross bar 27 is translated into vertical movement of the arms 25 and 26 by reason of the pivotal connection of the cross bars 27 and 28 to the arms 25 and 26. This vertical motion of the arms 25 and 26 causes the buttons 17 and 18 on the switch 16 to be selectively depressed depending upon the direction of rotation of the shaft 35 and the cross bar 27.

As will be seen from Figure 1, the receptacle 10 has been formed with a pair of mounting flanges which are apertured as at 51 to affix the flange 50 and, consequently, the housing to a supporting surface. The receptacle 10 has further been provided with a pair of bosses which will receive the conduits carrying the necessary electrical connections for the switch 16.

As is now obvious, it will be seen that by my invention I have provided a new and improved explosion proof switch housing wherein the switchoperating mechanism is simple and inexpensive to manufactureyet is highly efiicient in operation and will give long use. Further, by reason of the parallelogram type actuating mechanism, it will be seen that the operating shaft of the housing may be placed at any vertical distance above the push buttons of the switch, and the parallelogram switch mechanism will still operate to efiiciently depress the selected button of the switch.

.What I claim is:

1. An enclosed switch housing for push button switches comprising a receptacle, a switch having a pair of push buttons mounted in said receptacle, a cover mounted on said receptacle, an aperture in said cover extending normal to .the axis of said buttons, a stem mounted for oscillation in said aperture, a handle mounted on the outer end of said stem externally of said cover, push button actuating mechanism operatively connected to the inner end of said stem, said mechanism comprising a pair of links aligned respectively with said buttons, and means for selectively moving said links axially of said buttons into and out of engagement therewith upon oscillation of said stem, said means comprising upper and lower cross bars pivotally connected at each end to said links, a notch centrally located in the upper edge of said upper bar, and

a notch centrally located on the lower edge of said lower bar, said stern being formed with a portion positioned in the notch in said upper bar and having operative connection thereto, whereby said bar will be oscillated when said stem is oscillated, a pivot member being received in said notch on the lower edge of said lower cross bar, said pivot member extending in a direction transversely to the axis of said buttons and being fixedly mounted in said cover, whereby said links "will, be. selectively moved into and out of engagement with said buttons in a parallel linear pattern to selectively depress said buttons when said stem is oscillated.

2. An enclosed switch housing and push button switch operating mechanism as defined in claim 1, wherein the notch in said upper cross bar is of rectangular formation, and said stem is formed with a fiat portion cooperable with said rectangular formation.

3. An enclosed switch housing for electrical push button switches comprising a boxlike receptacle open at the top, a cover mounted on the open top of said receptacle, a push button switch mounted in said receptacle, a stem journalled in one side wall of said cover and being provided at its outer end with an actuating handle located exteriorly of the cover, a pivot support member fixedly mounted in the cover below said stem and extending in parallel relation thereto, said stern and pivot support being aligned in a plane positioned between the buttons of said switch, a cross bar pivotally mounted intermediate its ends on said pivot support member, a vertically disposed link pivotally connected to each end of said cross bar, said links being arranged in alignment respectively with the buttons of said switch, an upper cross bar operatively connected to the inner end of said stem for oscillation therewith, said upper bar being pivotally connected at its ends to the upper ends of said links whereby, upon oscillation of said stem, said links are moved in parallel linear pattern into and out of engagement with the buttons of said switch.

References Cited in the file of this patent UNITED STATES PATENTS 2,603,734 Petree July 15, 1952 

